This invention relates to a device for closing a top central opening in a vessel. More particularly, this invention relates to a vessel closure apparatus comprising a sealing valve in the form of a spherical dome carried by one end of a control arm inside the vessel and cooperating with a seat around the vessel opening; and a valve operating mechanism comprising a hollow rotary support housed about its axis of rotation in a leaktight bearing on the wall of the vessel and connected to the other end of the control arm by means of a device permitting axial displacement of the valve in relation to its seat. This invention also relates to the application of a closure device of this type to a storage hopper in a shaft furnace charging installation.
A shaft furnace charging installation provided with a closure device of the type described above is described in European Patent No. EP0062770 corresponding to U.S. Pat. No. 4,514,129, assigned to the assignee hereof, all of the contents of which are incorporated herein by reference. The storage hopper in this patent is provided with top and bottom sealing valves of the type described above and shown in detail in FIG. 4 of that patent.
In that prior patent, the bottom sealing valve moves in a valve cage outside the vessel, while the top sealing valve is always disposed inside the vessel. The top sealing valve includes the disadvantage of reducing the capacity of the vessel, because when it is opened, it is turned about an axis at right angles to the axis of the hopper in order to assume a substantially vertical position. The filling of the hopper must therefore be interrupted before the poured cone of charging material touches the valve in its open position. In other words, the capacity of the hopper is reduced by a certain volume, which can be characterized as "wasted space". This means that a larger hopper must be provided in order to introduce a predetermined quantity of material into the furnace for each cycle.